MOCA GPS-MEA

LesGawlik

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Why would the MOCA ever be different from the GPS MEA?
 
Why would the MOCA ever be different from the GPS MEA?

Because they want to able to talk to you at the MEA?

Low altitude RNAV only routes are identified by the prefix "T", and the prefix "TK" for RNAV helicopter routes followed by a three digit number (T-200 to T-500). Routes are depicted in blue on the IFR Enroute Low Altitude Charts. RNAV route data (route line, identification boxes, mileages, waypoints, waypoint names, magnetic reference courses and MEAs) will also be printed in blue. Magnetic reference courses will be shown originating from a waypoint, fix/reporting point or NAVAID. GNSS MEA for each segment is established to ensure obstacle clearance and communications reception. GNSS MEAs are identified with a "G" suffix.
 
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If GPS MEAs ensure obstacle clearance and coms reception, what' the difference between a GPS MEA and a regular MEA? Some of the GPS MEAs are the same altitude as MOCAs.
 
If GPS MEAs ensure obstacle clearance and coms reception, what' the difference between a GPS MEA and a regular MEA? Some of the GPS MEAs are the same altitude as MOCAs.

Victor Airway MEA’s also require ‘communication.’ GPS MEA being the same as MOCA would indicate there is communication available at that altitude.
 
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MOCAs still provide VOR reception with in 22 NM of the station.
You're always 12,000 miles from the GPS station.
 
Neither MEAs nor MOCAs guarantee communication. They are to stop loud noises from happening.


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Neither MEAs nor MOCAs guarantee communication. They are to stop loud noises from happening.
Nope. MEA provides the following:
1. Obstruction clearance.
2. Minimum ROC from one altitude to the other.
3. Com and navigation facility requirements. Note that there are allowable gaps in both.
4. Multiples of 100'.
 
This has been discussed multiple times here and in other aviation forums. VHF communications is one thing you get at the MEA (and above) but not necessarily at the MOCA, as others have stated.

- Martin
 
MOCAs still provide VOR reception with in 22 NM of the station.
You're always 12,000 miles from the GPS station.
Not if you have an Elon rocket and enter DIrect->To.
 
Okay, so the only difference is that the MOCA guarantees nav reception within 22 nm of the station and the GPS altitude does not. Both guarantee obstable clearance.
 
Nope. MEA provides the following:
1. Obstruction clearance.
2. Minimum ROC from one altitude to the other.
3. Com and navigation facility requirements. Note that there are allowable gaps in both.
4. Multiples of 100'.

From the Instrument Procedures Handbook:
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Only the last sentence address comms, and does not ‘assure’ it like the first sentence does for Nav coverage and obstacle clearance.
Damn near every other site I hit say “comms are not guaranteed at the MEA”. Where is it published that the MEA ‘guarantees’ comms?

Always willing to learn...


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Where is it published that the MEA ‘guarantees’ comms?

Always willing to learn...


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TERPs 8260.3E:

"14-1-9. Minimum En Route IFR Altitudes. An MEA will be established for each segment of an airway/route from radio fix to radio fix. The MEA will be established based upon obstacle clearance, adequacy of navigation facility performance, and communications requirements. Segments are designated West to East and South to North. Altitudes must be established in 100-foot increments (for example, 2001 feet becomes 2100)."

"Communications requirements" means what a particular ARTCC requires. It they are willing to accept a VHF/UHF communications gap at MEA, then flight inspection won't increase the MEA above what is required for obstacle clearance. But, if the ARTCC finds a communications gap unacceptable for a given airway segment, then flight inspection will determine the minimum altitude for continuous VHF/UHF communications and increase the MEA accordingly.
 
TERPs 8260.3E:

"14-1-9. Minimum En Route IFR Altitudes. An MEA will be established for each segment of an airway/route from radio fix to radio fix. The MEA will be established based upon obstacle clearance, adequacy of navigation facility performance, and communications requirements. Segments are designated West to East and South to North. Altitudes must be established in 100-foot increments (for example, 2001 feet becomes 2100)."

"Communications requirements" means what a particular ARTCC requires. It they are willing to accept a VHF/UHF communications gap at MEA, then flight inspection won't increase the MEA above what is required for obstacle clearance. But, if the ARTCC finds a communications gap unacceptable for a given airway segment, then flight inspection will determine the minimum altitude for continuous VHF/UHF communications and increase the MEA accordingly.

Calling @LesGawlik ,the OP's attention to this.
 
I should add that flight inspection also has to determine that VOR reception is adequate for a given Victor Airway segment. If not, they return it to the designers to decide whether to create a navigation gap or raise the MEA for continuous VOR reception.
 
TERPs 8260.3E:

"14-1-9. Minimum En Route IFR Altitudes. An MEA will be established for each segment of an airway/route from radio fix to radio fix. The MEA will be established based upon obstacle clearance, adequacy of navigation facility performance, and communications requirements. Segments are designated West to East and South to North. Altitudes must be established in 100-foot increments (for example, 2001 feet becomes 2100)."

"Communications requirements" means what a particular ARTCC requires. It they are willing to accept a VHF/UHF communications gap at MEA, then flight inspection won't increase the MEA above what is required for obstacle clearance. But, if the ARTCC finds a communications gap unacceptable for a given airway segment, then flight inspection will determine the minimum altitude for continuous VHF/UHF communications and increase the MEA accordingly.

So, (to flog an unresponsive equine...) the pilot won’t know if there’s an acceptable comm gap on an airway. Therefore comms are not ‘guaranteed’. They’re probably most likely, but still...


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I understand MEAS. I was looking for the difference between the MOCA and the GPS Min Alt. It appears that the MOCA guarantees NAV reception 22 nm from the stations, GPS Min Alt doesn't care. In looking at some charts, it seemed like the MOCA was often the GPS Min Alt.
 
So, (to flog an unresponsive equine...) the pilot won’t know if there’s an acceptable comm gap on an airway. Therefore comms are not ‘guaranteed’. They’re probably most likely, but still...


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Yup. Bovines get it to.:lol:
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